SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27eff4495f3ecd1e7ac56e9f9c3fdf06ba51cb3626907dd378d5cff41a2f6a1b' 
  AND token = 'P2JWTQ9YDeUIZlHh2ejm+mx/ztvCosaKYmXUJbo9b18=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}